Interesting, both the Qt and Java ones seem to use chaining, but I guess they're not designed with these sorts of extremely demanding applications in mind.
Open addressing does do more comparisons than chaining. It used to save time to traverse the linked list rather than to spend CPU cycles on those additional comparisons. Now, because CPU cycles are relatively cheaper, the opposite is true.
The reason the Qt and Java hashtables use chaining is simply that the code in question was initially written back when the tradeoff ran the other way.
These indirections have always been costly on any machine with virtual memory. TLB misses aren't free. I'd have put any estimate on the tradeoff being the other way around to more than 25 years.